Test

[zenpi314]

This is just to see if this works.

Sorry if I bother someone with it.

Arno

[Norm]

Well the pic worked....does the mill?

             ( :>) Norm

[TomW]

Arno;

We love photos of projects! Thats kind of the whole point. Can you give us some details on how you did it and how it performs?

Cheers.

TomW

[jmk]

 Maybe he is just testing us? So what did you make there?

[zenpi314]

Oh my.

It was basically a test for myself to see if it would post my diary. I did not expect it to pop up under the diary page. I would have added more information.

It is my first prop. The blades are obviously cut from a 4" pvc pipe, and they are about 2 feet long. The generator is an ametek 30V motor. At the moment it is running two little lights, just to have some load on it, but hopefully it will turn into a 12 volt battery charger for when a hurricane dropkicks us to the dark ages (which happens every summer at least once or twice).









I also experimented a little with filling the pvc with foam and covering it with fiberglass. Some success, but not very impressive yet. I read a lot about attempts to make fiberglass blades, but have seen little result yet (apologies to all who succesfully made their fiberglass blades;)

The next step is probably to make my own permanent magnet alternator. That will be with a bigger set of props (about 2m in diameter). Not sure yet if it will be pvc/fiberglass or a set of the fiberglass blades from China (ebay).

Any suggestions for alternator? Number of magnets/coils, wire size etc?

I have 24 rare earth magnets of 1.5 x 0.75 x 0.5 (I believe) and it will run on a 2 meter prop, charging a 12 volt battery.

Thanks for responding, and for all the helpfull information already posted on this forum.

Arno

potpower.com

[zenpi314]

Just to add a little more.

I also installed a small weather station to check on the windspeed. I know it is poor in Florida, hence no commercial turbines there, but it can hopefully give me some more insight in the amount of watts I can pull out of certain windspeeds.

BTW, how do people get information on the rpm's of their props? I might be able to count it up to 150 or so, but will lose track soon after that. When the wind picks up, it is just a blur.

Is it a linear property? So that, for example, when 5 volts is generated at 100 rpm, I know that the prop is running at 500 rpm, if I get 25 volts?

Sorry, for my ignorance. I have no background in mechanics or electronics, but I won't let that stop me from having fun with this.

Clear skies,

Arno

[jmk]

  I know what you mean about the diary thing. I thought the same thing too when I first put something in. The wind turbine looks good. It's to bad that there isn't wind until there is to much wind. At least you are getting something out of it. The voltage and rpm does go equally up in proportion but someone else can explain it better.  

[zenpi314]

Thanks JMK,

It is nice to know that I'm not alone in clueless land;)

Of course I don't mean to imply that you are clueless. Its just that things might seem obvious for seasoned users, but can be somewhat confusing for a newbie. I will get there though, just as you did. Thanks.

Arno

[jmk]

 Looks like the big wind is coming your way.

[alancorey]

For a DC motor like that used as a DC generator, the output voltage is pretty much linearly proportional to the RPM.  You should be able to establish a constant that you multiply by after a little bench testing from known RPMs.  An electric drill that you know the RPMs of can work, just don't trust that it's accurate to the label specs like I did.  A low-tech approach I've seen mentioned here is to get a piece of threaded rod (all-thread to some) with a known threads/inch.  Couple it to the shaft, then put a nut on it.  Get a stopwatch or second hand ready, spin it up, grab the nut and see how far it moves along the rod in some convenient amount of time.  Do the math to convert threads/inch, distance and time to RPM.

All that goes out the window when you put an electrical load on it though.  A load will drag down the voltage and mess up your reading.

For a generator that's putting out AC (axial flux or motor conversions), you look at the frequency of the AC to get the RPM.  The voltage will drop with load, but the frequency will be real.

If you were to look at the output of your motor with an oscilloscope you might be able to see some noise spikes from the commutator riding on the DC.  If you could pick those off by capacitive coupling and feed them to a frequency counter you might have something that could work.  For either frequency counter method you'll need to figure out the relationship between RPM and HZ, but once you do it will stay constant.

  Alan

[zenpi314]

Wow, thanks Alan.

Lot of information to try.

It looks that without a load I can do the best counting I can, at the highest possible speed, and then extrapolate to other speeds.

With a load added, it gets more complicated. Maybe the threaded rod is a viable first option. The oscilloscope option will have to wait until I get one, or find someone willing to share.

To get a constant wind speed I might have to hook it up to a car. (That should be fun)

Thanks again, I will plug along.

Arno

[zenpi314]

We had a couple of nice breezes, but nothing to write home about (or this forum).

At the moment we are dealing with fog-like conditions due to everglades fires. It is giving us some really nice sunsets.